The present invention relates to a subsea control cable, comprising an outer circular-cylindrical sheath and cables, ducts etc. arranged within the sheath, and at least one weight element.
Subsea control cables of this kind, or umbilicals as they are often called, are widely used in offshore oil and gas recovery. The control cable is designed to transport chemicals, hydraulic fluid, electric power and/or electrical control and pilot signals. In particular in those cases where the control cable is designed to extend from a floating structure, for example, a ship, on the sea surface down to a subsea structure on the sea floor, it is essential that the control cable has a particular course, so that relative movements between the ship and the sea floor do not exert excessively large loads on the control cable. To achieve this course, weight elements are hung onto parts of the control cable whilst other parts of the control cable are preferably equipped with floats.
The most common course for the control cable in such a case is a so-called S-shape or wave-shape. In this case, the control cable extends approximately vertically from the ship and then extends in a gentle curve a short distance upwards, in order subsequently to extend in a gentle curve downwards again and finally into an approximately horizontal course at the sea floor. This manner of laying a control cable and the effect this gives are well described in the technical literature, and are well known to persons versed in the art, and will therefore not be described in more detail here.
The attached weight elements and/or floats involve complicated operations when the cable is to be laid, which leads to high costs. Moreover, the result is a number of projecting elements on the surface of the control cable, which may easily become stuck on installations and possibly pulled off